This is a new personality test that still tests for for the 16 4-letter types. But it will test for 16 cognitive functions instead of the 8 that most people are probably used to. Basically, the idea is that your brain will have 4 ways of functioning that come most naturally, somewhat like the dominant & auxiliary functions in MBTI.
If you're interested, try it!http://www.erikthor.com/test/flow-type-full-version/